1 files changed, 104 insertions, 0 deletions
diff --git a/webrtc/modules/desktop_capture/screen_capturer_helper.cc b/webrtc/modules/desktop_capture/screen_capturer_helper.cc
new file mode 100644
index 0000000000..fa7096d24d
--- /dev/null
+++ b/webrtc/modules/desktop_capture/screen_capturer_helper.cc
@@ -0,0 +1,104 @@
+/*
+ *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/desktop_capture/screen_capturer_helper.h"
+
+#include <assert.h>
+#include <algorithm>
+
+#include "webrtc/system_wrappers/include/logging.h"
+
+namespace webrtc {
+
+ScreenCapturerHelper::ScreenCapturerHelper()
+    : invalid_region_lock_(RWLockWrapper::CreateRWLock()),
+      log_grid_size_(0) {
+}
+
+ScreenCapturerHelper::~ScreenCapturerHelper() {
+}
+
+void ScreenCapturerHelper::ClearInvalidRegion() {
+  WriteLockScoped scoped_invalid_region_lock(*invalid_region_lock_);
+  invalid_region_.Clear();
+}
+
+void ScreenCapturerHelper::InvalidateRegion(
+    const DesktopRegion& invalid_region) {
+  WriteLockScoped scoped_invalid_region_lock(*invalid_region_lock_);
+  invalid_region_.AddRegion(invalid_region);
+}
+
+void ScreenCapturerHelper::InvalidateScreen(const DesktopSize& size) {
+  WriteLockScoped scoped_invalid_region_lock(*invalid_region_lock_);
+  invalid_region_.AddRect(DesktopRect::MakeSize(size));
+}
+
+void ScreenCapturerHelper::TakeInvalidRegion(
+    DesktopRegion* invalid_region) {
+  invalid_region->Clear();
+
+  {
+    WriteLockScoped scoped_invalid_region_lock(*invalid_region_lock_);
+    invalid_region->Swap(&invalid_region_);
+  }
+
+  if (log_grid_size_ > 0) {
+    DesktopRegion expanded_region;
+    ExpandToGrid(*invalid_region, log_grid_size_, &expanded_region);
+    expanded_region.Swap(invalid_region);
+
+    invalid_region->IntersectWith(DesktopRect::MakeSize(size_most_recent_));
+  }
+}
+
+void ScreenCapturerHelper::SetLogGridSize(int log_grid_size) {
+  log_grid_size_ = log_grid_size;
+}
+
+const DesktopSize& ScreenCapturerHelper::size_most_recent() const {
+  return size_most_recent_;
+}
+
+void ScreenCapturerHelper::set_size_most_recent(
+    const DesktopSize& size) {
+  size_most_recent_ = size;
+}
+
+// Returns the largest multiple of |n| that is <= |x|.
+// |n| must be a power of 2. |nMask| is ~(|n| - 1).
+static int DownToMultiple(int x, int nMask) {
+  return (x & nMask);
+}
+
+// Returns the smallest multiple of |n| that is >= |x|.
+// |n| must be a power of 2. |nMask| is ~(|n| - 1).
+static int UpToMultiple(int x, int n, int nMask) {
+  return ((x + n - 1) & nMask);
+}
+
+void ScreenCapturerHelper::ExpandToGrid(const DesktopRegion& region,
+                                        int log_grid_size,
+                                        DesktopRegion* result) {
+  assert(log_grid_size >= 1);
+  int grid_size = 1 << log_grid_size;
+  int grid_size_mask = ~(grid_size - 1);
+
+  result->Clear();
+  for (DesktopRegion::Iterator it(region); !it.IsAtEnd(); it.Advance()) {
+    int left = DownToMultiple(it.rect().left(), grid_size_mask);
+    int right = UpToMultiple(it.rect().right(), grid_size, grid_size_mask);
+    int top = DownToMultiple(it.rect().top(), grid_size_mask);
+    int bottom = UpToMultiple(it.rect().bottom(), grid_size, grid_size_mask);
+    result->AddRect(DesktopRect::MakeLTRB(left, top, right, bottom));
+  }
+}
+
+}  // namespace webrtc